Ovarian cancer has an extremely high mortality rate due it its late stage of diagnosis. Characterizing molecular events of the early precursor lesions and the stem cell niche is a first and necessary step to generating novel strategies for early detection, chemoprevention and surgical intervention in the natural history of these neoplasms. Hence, the proposed study aims at addressing a fundamental question in ovarian tumor development which is defining the molecular signature of precursor lesions and tumor initiating cells in ovarian cancer. Towards this, we are using genome-wide approaches to determine the expression of noncoding RNAs and will further determine their expression in serum in order to evaluate them as biomarkers for early detection. This is the first time that a unique murine model of ovarian cancer is being used to comprehensively characterize the changes in miRNA expression through various stages of tumor progression. This project will make a significant impact on identifying new molecular pathways for early diagnosis, which is critical in reducing the disease mortality and chemoprevention. In summary, successful completion of the proposed study would lead not only to better early detection but also development of chemopreventative methods, which could significantly impact the current prognosis of ovarian cancer patients.